A319243 Expansion of Product_{k>0} (1 - x^(k^2))/(1 + x^(k^2)).

1, -2, 2, -2, 0, 2, -2, 2, 0, -4, 6, -6, 4, 2, -6, 6, -6, 2, 4, -6, 8, -6, -2, 6, -8, 8, -2, -4, 8, -10, 6, 2, -6, 6, -2, -6, 8, -6, 2, 6, -8, 6, -2, -6, 8, -4, -2, 10, -14, 8, 0, -6, 16, -14, 4, 2, -16, 18, -2, -10, 24, -30, 14, 4, -20, 34, -26, 2, 16, -30, 26, 2, -20

Offset

0,2

Links

Table of n, a(n) for n=0..72.

Formula

Convolution inverse of A103265.

Prog

(PARI) N=99; x='x+O('x^N); Vec(prod(k=1, sqrtint(N), (1-x^(k^2))/(1+x^(k^2))))

Crossrefs

Product_{k>0} (1 - x^(k^m))/(1 + x^(k^m)): A002448 (m=1), this sequence (m=2), A319244 (m=3).

Cf. A103265.

Sequence in context: A317528 A246793 A335185 * A307521 A328995 A036476

Adjacent sequences: A319240 A319241 A319242 * A319244 A319245 A319246

Keyword

sign

Author

Seiichi Manyama, Sep 15 2018

Status

approved